1. Field of the Invention
The present invention relates to a method of manufacturing an organic light emitting display device, and more specifically, to packaging of an organic light emitting display device.
2. Description of the Related Technology
In general, an organic light emitting display (OLED) device includes a substrate having a pixel region and a non-pixel region, and another substrate arranged to be opposite to and attached to the substrate with a sealant such as an epoxy for its encapsulation.
The pixel region of the substrate includes multiple light-emitting elements in a matrix form between a scan line and a data line. The light-emitting element may include an anode electrode and cathode electrode, and an organic thin film layer formed between the anode electrode and cathode electrode. The organic thin film layer may include an hole transport layer, an organic light-emitting layer and an electron transport layer.
The light-emitting elements described above are susceptible to hydrogen and oxygen because it contains organic materials. In addition, the cathode electrode is easily oxidized by moisture in the air since it is made of metal materials, thus causing deterioration in electrical and light-emitting properties. To prevent the above problems, an OLED may have a powder-type moisture absorbent or a film-type moisture absorbent on a vessel manufactured in the form of a metal material can or cup, or a substrate made of glass, plastic, etc. to get rid of moisture, oxygen and hydrogen penetrated from the outside.
However, the method of coating the powder-type moisture absorbent needs complicated processes and raises cost for its materials and the processes. In addition, the method increases the thickness of the display device and is difficult to be applied to a top emitting light-emitting type. In addition, the method of attaching the film-type moisture absorbent has a limited ability to eliminate all the moisture and also has low durability and reliability, thus making it difficult to be applied to mass production.
A method has been proposed which encapsulates light-emitting elements by forming side walls with frits to overcome the above problems. International patent application No. PCT/KR2002/000994 (May 24, 2002) discloses an encapsulation container formed with side walls using a glass flit and a manufacturing method thereof. Korean patent laying-open gazette No. 2001-0084380 (Sep. 6, 2001) discloses a flit frame encapsulation method using a laser. Korean patent laying-open gazette No. 2002-0051153 (Jun. 28, 2002) discloses a packaging method of encapsulating an upper substrate and a lower substrate with a frit layer using a laser.
In a method of encapsulating light-emitting elements with a frit, an encapsulation substrate coated with the flit is attached to another substrate having light-emitting elements and a laser beam is irradiated on onto the back surface of the encapsulation substrate so that the frit is fused and attached to the substrate.
The temperature of the substrate is kept lower than that of the encapsulation substrate, since the laser reaches the substrate through the encapsulation substrate and the frit. For example, when the laser is irradiated, the temperature of the encapsulation substrate rises up to about 1000° C., but the temperature of the substrate only rises to about 600° C. Thus, the frit may be attached to the substrate without being completely fused. An interfacial adhesive strength between the frit and substrate may become weak, so that the display device is easily separable even when a slight impact is applied thereto or a force is applied to either of the substrate or encapsulation substrate.
In a method of attaching the frit on the substrate using a laser, the laser is illuminated onto the frit. However, in such a method, the laser beam is focused on the mid-portion of the width of the frit, and thus the power of the laser is weak on edges of the frit, which may lead to incomplete curing of the frit. The discussion in this section is to provide background information of the related technology and does not constitute an admission of prior art.